1. Field of the Invention
This invention relates to verifying read optical indicia, and particularly to verification of optical character recognition of optical code reads using acquired and stored image data.
The invention expands on methodologies and systems used to verify RFID reads as described in U.S. application Ser. No. 10/385,941 titled “SYSTEMS AND METHOD FOR VERIFYING RFID READS” and having a common assignee.
2. Description of the Related Art
Radio frequency identification (RFID) is an area of automatic identification in which a transponder, known generally as a tag, attached to an object communicates wirelessly with an RFID reader. RFID technology is used in a variety of applications including retail, industrial, transportation, tracking, security, animal identification and individual identification. Transfer of data via RFID technology may be used, for example, in indicating the presence of the object, such as in electronic article surveillance (EAS), for obtaining data associated with the object or for identifying the object. In an automatic identification system the tag is typically programmed with unique information, such as encoded data including an identifying code. The reader includes an antenna which emits radio carrier signals to activate the tag and read data from it, and a decoder for decoding the data read. The tag responds to the signal by modulating the carrier signal in accordance with the encoded data.
RFID technology allows for non-contact reading. The RFID reader may be a mobile reader, such as a hand-held reader, or a stationary reader such as a reader located in a tunnel, a door portal or a toll booth. The electromagnetic field generated by the antenna may be constant or activated by actuation means such as a sensor or a trigger. Advantages to RFID technology include non-contact reading without the need for line-of-sight interrogation.
The RFID reader and tag may be configured to operate using inductive coupling, electrostatic coupling, or electromagnetic coupling, in which induction of a current in a coil, induction of a voltage on a plate or a magnetic field, respectively, is used as a means for transferring data and/or power. The tag may be passive, in which case it contains no internal power source and is powered by the carrier signal radiated from the reader, or active, where it uses a battery for a partial or complete source of energy. The operational distance between the transponder and the reader depends on the configuration of the reader and tag used, as well as the frequency and power of the transmitted signals. Also, depending on the configuration of the RFID system, there may not be a need to orient the tag in a particular orientation for successful reading of the tag by the reader.
While the ability of the RFID reader to read a tag from an object while the object is typically located remote from the reader, not necessarily in a line-of-sight of the reader, and without orienting the tag in a particular orientation is advantageous in many applications, it is very possible that the reader might read a tag associated with an object that was not intended to be processed by the reader, resulting in a faulty read. In applications in which the read tag data is further processed, a faulty read will result in processing of faulty data, causing undesirable results, such as inaccurate inventories, charging an incorrect price for a consumer item, processing an unintended library book, charging a toll to an unintended vehicle, etc. Furthermore, noise, due to environmental conditions including moisture in the air and intervening objects, may corrupt data being read by the reader.
Accordingly, it is an object of the present invention to provide a system for verifying that a tag read by RFID methodology corresponds to the tag that was intended to be read and processed.
Also susceptible to faulty reads due to lack of accuracy and reliability are optical code readers that image an optical code and use optical character recognition (OCR) to recognize the code and generate a corresponding textual code. Recognition of each character has an associated error rate. The error rate associated with a string of characters is compounded by the error rate that corresponds to each character in the string. Accuracy in imaging and recognizing the characters of an optical code is affected by a variety of factors, such as illumination of the field of view, background lighting, code design, print quality of the optical code, cleanliness of the optical code and environment, font of the characters, reflectivity of a sticker on which the optical code is printed, code placement, contour of a surface on which the optical code is affixed and flatness of the optical code, image noise and distortion, etc. When the above factors are not ideal, an OCR module performing the OCR processing may have difficulty differentiating between several interpretations of individual characters and may independently select the interpretation representing the most probable textual code.
Accordingly, it is an object of the present invention to provide a system for verification of an optical code read by OCR processing, and/or to efficiently and accurately select a code from a plurality of possible codes corresponding to an imaged code which are generated by OCR processing.
Furthermore, it is an object of the present invention to provide a system and method for using an imaging device for identifying an object bearing an identifying optical code having increased accuracy and decreased processing time.